System for absorbing and distributing side impact energy utilizing an integrated battery pack

ABSTRACT

An energy absorbing and distributing side impact system for a vehicle includes: first and second side sills, each of the first and second sills comprising multiple longitudinal channels, at least an upper longitudinal channel positioned above a vehicle floor panel and at least a lower longitudinal channel positioned below the vehicle floor panel; a battery enclosure mounted between front and rear suspensions of the vehicle, the battery enclosure having a first side member attached to the first side sill, and a second side member attached to the second side sill; cross-members integrated into the battery enclosure; and one or more bolts each extending though a respective opening in one of the cross-members and extending to an opposite side of the vehicle floor panel from the cross-member.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims benefit of the filing date of: U.S. patent application Ser. No. 14/168,351, filed Jan. 30, 2014, U.S. patent application Ser. No. 13/308,300, filed Nov. 30, 2011, and U.S. Provisional Application Ser. No. 61/426,254, filed Dec. 22, 2010, the disclosure of each of which (including material incorporated therein by reference) is incorporated herein by reference for any and all purposes.

BACKGROUND OF THE INVENTION

Modern vehicles use a variety of structures to protect the vehicle's occupants during a crash. Some of these structures are used to control the transmission of the crash energy to the passenger compartment while other structures, such as seat belts, head restraints, and air bags, are intended to restrain passenger movement during a crash, thereby preventing the passengers from hurting themselves as their bodies react to the crash forces. Side impact collisions present a particularly challenging problem to vehicle safety engineers, both due to the relatively low position of the rocker panels on many small vehicles as well as the difficulty of implementing an impact resistant side structure while taking into account vehicle doors and doorways.

U.S. Pat. No. 6,676,200, issued 13 Jan. 2004, discloses an automotive structure utilizing inner and outer rocker panels, a floor pan joined to the inner rocker panels, and a plurality of cross-members that extend laterally across a portion of the vehicle body. The cross-members include energy absorbing extensions designed to absorb side impact loads.

An alternate approach to achieving impact resistance is disclosed in U.S. Pat. No. 6,793,274, issued 21 Sep. 2004, in which an energy management system is integrated within various automotive structural components, e.g., vehicle frames and rails. In particular, the disclosed system uses members or inserts that are in some way attached to selected structural components of the vehicle, the members designed to both absorb and redirect the impact energy encountered during a crash. The disclosed members also help to reinforce the components to which they are attached. The patent describes a variety of ways in which the disclosed members may be incorporated into a vehicle during the manufacturing process.

U.S. Pat. No. 7,090,293, issued 15 Aug. 2006, attempts to achieve improved occupant protection through a seat assembly that is designed to provide side impact rigidity and resistance to rocker override and side impact intrusions. The disclosed seat assembly includes a frame track, a frame base slidably engaged to the frame track, a frame back rotatably engaged to the frame base, and a rear lateral support assembly that includes a support frame attached to the rear portion of the frame base. The support frame includes a tubular member that is designed to engage with a vehicle rocker panel during impact, thereby providing additional rigidity and strength to the vehicle.

U.S. Pat. No. 8,007,032, issued 30 Aug. 2011, discloses an automotive energy absorbing side structure that includes a wide-based B-pillar with an internal reinforcing tube, a rocker with an internal bulkhead, a rear rocker, and at least one cross-member extending inward from the rocker. The disclosed cross-members are designed to transfer impact loads to the floor, the cross-members and the tunnel brace.

Although vehicle manufacturers use a variety of structures and components to protect a vehicle's occupants during a side impact collision, typically these approaches provide only limited protection while significantly increasing vehicle weight. Accordingly, what is needed is a system that provides superior vehicle occupant safety, particularly from side impact collisions, while adding minimal weight from impact resistant dedicated structures. The present invention provides such a system.

SUMMARY OF THE INVENTION

In a first aspect, an energy absorbing and distributing side impact system for a vehicle includes: first and second side sills, each of the first and second sills comprising multiple longitudinal channels, at least an upper longitudinal channel positioned above a vehicle floor panel and at least a lower longitudinal channel positioned below the vehicle floor panel; a battery enclosure mounted between front and rear suspensions of the vehicle, the battery enclosure having a first side member attached to the first side sill, and a second side member attached to the second side sill; cross-members integrated into the battery enclosure; and one or more bolts each extending though a respective opening in one of the cross-members and extending to an opposite side of the vehicle floor panel from the cross-member.

Implementations can include any or all of the following features. The battery enclosure is an aerodynamic device has a design that improves aerodynamic performance of the vehicle. A bottom of the battery enclosure is substantially flat. Front wheel arch edges on the battery enclosure are radiused to allow air from a front wheel to transition to an underside of the vehicle. The energy absorbing and distributing side impact system further comprising a gasket material that covers a gap formed between a top of the battery enclosure and an underside of the vehicle floor panel. The energy absorbing and distributing side impact system further comprising a seat mounting structure on the opposite side of the vehicle floor panel from the cross-member, the seat mounting structure held by at least the one or more bolts. The seat mounting structure further comprises at least one threaded seat mount. The bolt is held by a nut on a same side of the vehicle floor panel as the seat mounting structure. The energy absorbing and distributing side impact system further comprising a sub-frame mount integrated into the battery enclosure. The energy absorbing and distributing side impact system further comprising a sub-frame bushing mounted in double shear with a structure on a bottom plate of the battery enclosure. The battery enclosure is an integral part of a load path for managing loads in frontal impact. The energy absorbing and distributing side impact system is configured so that a majority of the loads are fed from rails at a front of the vehicle into a torque box. The energy absorbing and distributing side impact system further comprising a secondary load path that feeds loads from a lower portion of the vehicle along a sub-frame and into a rear mount of the sub-frame coupled to the battery enclosure and to the torque box. The battery enclosure is configured to feed the loads along its members to the first and second side sills. A bottom plate of the battery enclosure is configured to provide sheer stiffness to mounting locations of a steering rack. The first side member is attached to the lower longitudinal channel of the first side sill and the second side member is attached to the lower longitudinal channel of the second side sill. Each of the cross-members comprises an upper portion and a lower portion, wherein a spacing between the upper and lower portions is configured to receive a mounting bracket for at least one battery module in the battery enclosure. Each of the first and second side members comprises at least first through fourth lumens, wherein at least the first, second and third lumens are arranged in an essentially vertical configuration, and wherein at least the fourth lumen is arranged outward of the third lumen. The cross-members segregate the battery enclosure into full-width sections and at least one other section, each of the full-width sections fitting two battery modules side-by-side in a direction of travel, the other section fitting two stacked modules.

In a second aspect, an energy absorbing and distributing side impact system for a vehicle includes: first and second side sills, each of the first and second sills comprising multiple longitudinal channels, at least an upper longitudinal channel positioned above a vehicle floor panel and at least a lower longitudinal channel positioned below the vehicle floor panel; and means for improving aerodynamic performance of the vehicle, for providing noise and thermal insulation, for providing a mounting structure for a seat in the vehicle, for providing an attachment for a sub-frame, for providing a load path for loads in a frontal impact, for providing protection of an occupant in a side impact, and for providing stiffness to a mounting location of a steering rack.

A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a simplified bottom view of an electric vehicle with a battery pack incorporated into the vehicle structure;

FIG. 2 provides a perspective view of a vehicle's undercarriage with the battery pack incorporated into the vehicle structure;

FIG. 3 provides a perspective view of a portion of a vehicle body and frame with the battery pack separated from the structure;

FIG. 4 provides a perspective view of the battery pack shown in FIGS. 1-3;

FIG. 5 provides a perspective view of the battery pack shown in FIGS. 1-4, with the top panel removed;

FIG. 6 provides a perspective view of the battery pack shown in FIGS. 1-5, this view showing three of the battery modules in place within the pack;

FIG. 7 provides a perspective, cross-sectional view of the battery pack shown in FIGS. 1-6 mounted under the floor panel of the vehicle shown in FIG. 3;

FIG. 8 provides a detailed cross-sectional view of one of the cross-members shown in FIG. 7;

FIG. 9 provides a detailed cross-sectional view of an alternate cross-member;

FIG. 10 provides a detailed cross-sectional view of an alternate cross-member;

FIG. 11 provides a detailed cross-sectional view of an alternate cross-member;

FIG. 12 provides a perspective view of the battery pack to rocker panel assembly;

FIG. 13 provides a cross-sectional view of the assembly shown in FIG. 12;

FIG. 14 provides a cross-sectional view of a structural support element;

FIG. 15 illustrates the sculpted leading edge of the battery pack in accordance with the invention;

FIG. 16 provides a perspective view of a sub-frame mount integrated into the battery pack;

FIG. 17 provides an alternate view of the sub-frame mount shown in FIG. 16;

FIG. 18 illustrates a vehicle frontal impact system utilizing the battery pack;

FIG. 19 provides a side view of the frontal impact system shown in FIG. 18;

FIG. 20 illustrates the use of the battery pack to enhance the rigidity of the steering rack mount;

FIG. 21 provides an alternate view from that shown in FIG. 20; and

FIG. 22 provides a cross-sectional view of a seat mounting structure mechanically coupled to the battery pack using structure from FIG. 14.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

In the following text, the terms “battery”, “cell”, and “battery cell” may be used interchangeably and may refer to any of a variety of different cell types, chemistries and configurations including, but not limited to, lithium ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel zinc, silver zinc, or other battery type/configuration. The term “battery pack” as used herein refers to multiple individual batteries contained within a single piece or multi-piece housing, the individual batteries electrically interconnected to achieve the desired voltage and capacity for a particular application. The term “electric vehicle” as used herein refers to either an all-electric vehicle, also referred to as an EV, plug-in hybrid vehicles, also referred to as a PHEV, or a hybrid vehicle (HEV), a hybrid vehicle utilizing multiple propulsion sources one of which is an electric drive system.

The present invention integrates a battery pack into an electric vehicle in order to add rigidity to the vehicle structure and significantly increase the vehicle's side impact resistance by absorbing and distributing the impact load throughout the battery pack structure. To achieve the desired level of structural rigidity, strength and impact resistance, preferably the battery pack is large relative to the overall dimensions of the vehicle and includes multiple cross-members as described in detail below. In a preferred embodiment of the invention illustrated in FIGS. 1-3, battery pack 101 not only transverses the width of the vehicle, i.e., from rocker panel to rocker panel, but also extends most of the distance between the front suspension 103 and the rear suspension 105. It will be appreciated that while smaller battery packs may be used with the invention, they may not provide the same level of side impact protection, depending upon their size and the number of integrated cross-members. In the illustrated embodiment, battery pack 101 is approximately 2.7 meters long and 1.5 meters wide. The thickness of battery pack 101 varies from approximately 0.1 meters to 0.18 meters, the thicker dimension applicable to those portions of the battery pack in which battery modules are positioned one on top of another, as described further below.

FIG. 4 provides a perspective view of battery pack 101 with the top enclosure panel 401 in place, panel 401 preferably providing a substantially airtight seal. Hollow side structural elements 403 are also visible, members 403 preferably including an extended region or lip 405 that is used to mechanically and thermally couple the side members 403 to the vehicle structure (not shown in this figure). FIG. 5 shows battery pack 101 with top member 401 removed, this view showing cross-members 501A-501H. The number of cross-members is based on the number of cells/cell modules that are to be encased within the battery pack as well as the desired structural characteristics of the battery pack. Preferably battery pack side members 403, including extended region 405, battery pack top panel 401 and battery pack bottom panel 505 are each fabricated from a light weight metal, such as aluminum or an aluminum alloy, although other materials such as steel may be used for some or all of the battery pack components. Bottom panel 505 may be welded, brazed, soldered, bonded or otherwise attached to side members 403, with the resultant joint between panel 505 and member 403 preferably being substantially air-tight as well as being strong enough to allow bottom panel 505 to support the batteries contained within the pack. Top panel 401 is typically attached to member 403 using bolts or similar means, thus simplifying battery replacement as well as allowing battery interconnects, battery pack components, cooling system components and other battery pack components to be repaired and/or replaced.

Cross-members 501A-501H provide several benefits. First and foremost relative to side impact resistance, members 501A-501H provide mechanical and structural strength and rigidity to the battery pack and to the vehicle to which the battery pack is attached. Additionally, cross-members 501A-501H help to segregate thermal events by providing a thermal barrier between groups of cells as well as minimizing gas flow between sections 503, sections 503 being defined by the cross-members, side members 403, top member 401 and bottom member 505. By segregating thermal events within smaller groups of cells, thermal runaway propagation is limited as is the potential for battery pack damage.

FIG. 6 shows a similar view to that provided by FIG. 5, with the inclusion of a couple of cell modules 601. In this illustration, a single module 601 is shown positioned within one of the seven, larger sections 503 of battery pack 101. Note that each large section 503 is designed to house a pair of battery pack modules 601. Additionally, in this illustration there are two modules 601 stacked one on top of the other in the front section 507 of pack 101. Note that in the preferred embodiment, each module 601 contains 370 individual cells, each cell utilizing an 18650 form factor. It should be understood, however, that this configuration is only exemplary of a preferred embodiment and that the invention is equally applicable to other configurations, for example utilizing batteries with a different form factor, a larger or smaller number of cells, individual cells versus modules, etc.

FIG. 7 provides a perspective, cross-sectional view of battery pack 101 mounted under floor panel 701 of vehicle 100. This view also provides additional views of the cross-members. As shown by the cross-sectional view, in the preferred embodiment cross-members 501A-501H do not utilize the same cross-section; rather the cross-section of each is optimized for each member's location within the pack. In general, cross-members 501A-501H may either be comprised of a single unit or, as preferred and illustrated, comprised of an upper member and a lower member. One or both members may be hollow, thus achieving the desired rigidity and strength while minimizing weight. It should be understood that not only can the configuration/design of the cross-members vary, depending upon their location within the pack, so can the materials comprising the cross-members. Therefore while cross-members 501A-501H are preferably fabricated from aluminum or an aluminum alloy, for example using an extrusion process, other materials (e.g., steel, ceramics, etc.) may also be used if such materials fit both the mechanical and thermal goals for the particular cross-member in question. Additionally, the lumens within one or more of the cross-members may be unfilled or filled with a high melting temperature, low thermal conductivity material (e.g., fiberglass or similar materials). Alternately, the lumens within the cross-members may include a liquid (e.g., water), the liquid being either stagnant or flowing. If stagnant, the liquid may be contained within the lumens themselves or, as preferred, contained within pouches that fit within the cavities. If the liquid is flowing, it is preferably contained within tubing that is inserted within the cross-member cavities and either coupled to a battery cooling system or used in a stand-alone circulation system.

In the preferred embodiment, and as illustrated in FIG. 7, cross-members 501D and 501E are larger than the other central cross-members. The reason for the increased size is to provide additional cross-member strength at those locations that are most critical to achieving the desired level of side-impact resistance. As shown in the detailed cross-sectional view of FIG. 8, in the preferred embodiment cross-members 501D and 501E are comprised of an upper member 801 that is attached to battery pack top panel 401 and includes a single lumen 803, and a lower member 805 that is attached to battery pack bottom panel 505 and includes a pair of lumens 807 and 809. In this embodiment, member 801 is approximately 19 millimeters high, 30 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Member 805 is approximately 54 millimeters high, 26 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters.

Cross-members 501B, 501C, 501F and 510G are slightly smaller than cross-members 501D and 501E, although they retain the basic shape of the larger cross-members. As shown in the detailed cross-sectional view of FIG. 9, these cross-members are comprised of an upper member 901 that is attached to battery pack top panel 401 and includes a single lumen 903, and a lower member 905 that is attached to battery pack bottom panel 505 and includes a pair of lumens 907 and 909. In this embodiment, member 901 is approximately 19 millimeters high, 16 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Member 905 is approximately 54 millimeters high, 16 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Note that the spacing between upper member 801 and lower member 805, and the spacing between upper member 901 and lower member 905, is used in the preferred embodiment to capture a battery module mounting bracket (not shown in FIGS. 8 and 9).

Cross-member 501A, located near the rear of battery pack 101 and illustrated in the detailed cross-section of FIG. 10, includes a first member 1001 that extends from battery pack lower panel 505 to battery pack top panel 401. Member 1001 is comprised of a large lower section 1003 and a small upper section 1005 with respective lumens 1007 and 1009. Section 1003 of member 1001 is approximately 54 millimeters high, 30 millimeters wide, and has a wall thickness of between approximately 2 and 4 millimeters. Section 1005 of member 1001 is approximately 29 millimeters high, 13 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Cross-member 501A also includes a second member 1011 that includes a single lumen 1013 as shown. Member 1011 is approximately 29 millimeters high, 16 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters.

Cross-member 501H shown in the detailed view of FIG. 11, is located near the front of battery pack 101 and between battery pack section 507 and the adjacent section 503. As section 507 is designed to house two battery pack modules, one on top of the other, this portion of battery pack 101 utilizes a different design which, in turn, affects the design of cross-member 501H. As shown, cross-member 501H includes an upper member 1101 that has a single lumen 1103, and a lower member 1105 that has a single lumen 1107. Member 1101 is approximately 54 millimeters high, 26 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters. Member 1105 is approximately 29 millimeters high, 26 millimeters wide, and has a wall thickness of between approximately 2 and 3 millimeters.

FIGS. 12 and 13 provide perspective and cross-sectional views, respectively, that illustrate the attachment of the battery pack 101 to vehicle structural side member 1201. In the preferred embodiment structural side member 1201 is comprised of a rocker panel, also referred to herein as a sill, which is formed from extruded aluminum or an aluminum alloy (although other materials such as steel may be used for members 1201). Preferably a seal or gasket is located between the top surface 1301 of side members 403 and the bottom surface 1303 of the top panel 401, thus achieving a substantially air-tight seal. An o-ring groove 1304 is visible in FIG. 13 for use with such a seal. In the illustrated embodiment, each side member 403 includes four lumens 1305-1308. Lower exterior lumen 1308 is positioned under the extended region 405 of side member 403. Lumen 1308 is perforated on upper surface 1309 and lower surface 1311, the perforations on these two surfaces being aligned such that bolts 1313, or similar means, may pass completely through lumen 1308, thereby allowing bolts 1313 to couple extended region 405 of member 403 to structural side member 1201 as shown. Bolts 1313 and channel nuts 1315 securely attach side members 403, and therefore battery pack 101, to the vehicle's structural members 1201. Preferably channel nuts 1315 are held in place during assembly using channel nut retainer 1317. In addition to providing a strong mechanical coupling, this approach allows battery pack 101 to be quickly and efficiently removed from underneath vehicle 101.

FIG. 14 provides a cross-sectional view of a structural support element 1400. A bolt 1402 penetrates a metallic sleeve 1404 that is welded to the structure. Bolt 1402 threads through a nut 1406, for example in a cross-member of the vehicle structure. This interface is then sealed at multiple interfaces when the bolt is tightened and provides additional clamping force to the battery mounts. Here, spacing between an upper member 1408 and a lower member 1410 is used to capture a battery module mounting bracket 1412.

FIG. 22 provides a cross-sectional view of a seat mounting structure mechanically coupled to the battery pack using structure from FIG. 14. In some implementations, a battery pack is used for facilitating through-bolting seat mountings. A seat mounting structure 2200 is mechanically coupled to the battery pack. Coupling the seat mounting structure 2200, and thus the vehicle seats (not shown, but attached via threaded seat mount 2202), to the battery pack provides greatly enhanced seat mount performance. As shown, the vehicle has a cross-member (i.e., structure 2200) with a threaded sleeve 2202 welded into it which provides the mount which the seat sits on top of and bolts into. From the opposing side and in close proximity to (as illustrated) or coaxially with the seat mount, a bolt 1402 penetrates a metallic sleeve 1404 that is welded to the structure. Bolt 1402 threads through the nut 1406 which is contained in the cross-member 2200 in the vehicle structure. This interface is then sealed at multiple interfaces when the bolt is tightened and provides additional clamping force to the battery mounts.

FIG. 15 illustrates the sculpted leading edge of the battery pack in accordance with the invention. In some implementations, a battery enclosure has an aerodynamic form. In accordance with at least one aspect of the invention, the battery pack of a vehicle is used as an aerodynamic device for improving the vehicle's overall aerodynamic performance. In a preferred embodiment, the bottom surface of the battery pack is flat, or substantially flat, and the front wheel arch edges are heavily radiused in order to allow air from the wheel wells to transition from the slow moving wheel arch edges to the underside of the vehicle. FIG. 5 illustrates this aspect of the invention, showing a sculpted leading edge 1500 of the battery pack, thereby creating an aerodynamic shape between the front wheel arch and the flat bottom of the pack. This design aids the purging of air from within the wheel arch. Note that sculpted front wheel arch edge 501 is also visible in FIGS. 1-3.

FIG. 16 provides a perspective view of a sub-frame mount integrated into the battery pack. FIG. 17 provides an alternate view of the sub-frame mount shown in FIG. 16. In some implementations, a sub-frame mount is integrated into a battery pack. The purpose of a rubber sub-frame bushing is to isolate the passenger compartment from the road inputs as well as to tune the overall dynamics of the suspension. The ability to tune the sub-frame bushing to act predictably in all cases is dependent on the rigidity of its mounting to the vehicle. By mounting a bushing using one mount surface and a bolt, the bolt and mount location is highly loaded in single shear. By adding an extra attachment to another component, this loading can be distributed among additional members and the mounting becomes stiffer. This in turn increases the performance of the bushing by allowing it to be more precisely tuned. In accordance with the invention, and as illustrated in FIGS. 16 and 17, this goal is achieved by mounting the sub-frame bushing in double shear with a piece of structure 1600 that is attached directly to the bottom plate of the battery enclosure. It will be appreciated that structure 1600 may either be separate from the bottom panel 607 of battery pack 601 and designed to be bolted to panel 607, or it may be fabricated as an integral part of the battery pack enclosure. Preferably this aspect of the invention is combined with a coaxial double screw fixture, thereby allowing the battery pack and sub-frame structure 1600 to be removed from the vehicle while retaining the sub-frame bushing attachment to the body-structure.

FIG. 18 illustrates a vehicle frontal impact system utilizing the battery pack. FIG. 19 provides a side view of the frontal impact system shown in FIG. 18. In some implementations, a battery pack is used in a frontal impact system. In a conventional hybrid or electric vehicle, the battery pack is isolated and not used as a load bearing member that contributes to frontal impact performance. In the present invention, however, the battery pack is made strong enough to resist forces from the front of the vehicle. Additionally, the battery pack strengthens the overall ability of the front torque boxes to distribute frontal loads into the sills of the vehicle. Accordingly, in another aspect of the invention, battery pack 601 is used as an integral part of the load path used for the management of loads in a frontal impact to protect the occupants during such an event. Preferably, and as shown in FIGS. 18 and 19, the majority of the loads are fed from the rails into the front torque box. The buckling stability and strength of this torque box is significantly increased by coupling the battery box in four locations to this structural member. In addition, a secondary load path feeds loads from the lower portion of the vehicle along the sub-frame and into the rear mount of the sub-frame that is coupled to the battery and the torque box using a single bolt. This allows the loads from a frontal impact to not only be input into the torque boxes, but into the battery. The battery then feeds the loads along its members to the sill sections of the vehicle and also stabilizes the torque boxes in this mode.

FIG. 20 illustrates the use of the battery pack to enhance the rigidity of the steering rack mount. FIG. 21 provides an alternate view from that shown in FIG. 20. In some implementations, the battery pack is used to enhance steering feel. The rigidity of the steering rack mounting is integral to providing high quality steering feel, response, and feedback from the road to the driver. In accordance with another aspect of the invention, and as illustrated in FIGS. 18 and 19, the structure of the battery pack, and more specifically the thick bottom plate of the battery pack, is used to provide exemplary shear stiffness in the y direction to the mounting locations of the steering rack in order to provide a more rigid and direct connection of the steering rack to the vehicle structure in order to resist opposite loads input from the road.

In a conventional vehicle, it is difficult to achieve the desired rigidity in the steering rack mounting without adding extra material, and therefore mass. In accordance with the invention, however, the shear stiffness of the bottom panel of the existing battery pack structure is used to stiffen the point at which the steering rack is mounted. By using a structure already present in the vehicle, the efficiency of the mounting is improved by coupling these components without the added mass which would be necessary to stiffen the steering rack mounting in a conventional configuration.

In some implementations, mounting the battery pack to the body structure provides a stiffness multiplier effect. In accordance with another aspect of the invention, the battery pack is designed to add not just its own stiffness but a multiple of it to the vehicle's body structure. This multiplier effect has been achieved through the manner in which the pack is mounted as well as the design of the pack which, in particular, is not designed to possess maximum stiffness in its own right, but to intentionally penalize that for the greater benefit of when it is attached to the body structure. This is achieved by balancing the relative thicknesses of the battery pack structure. To achieve the multiplier effect, the structure of the battery pack has been deliberately compromised as a stand-alone item for significantly greater contribution when attached to the body structure. That the pack contributes not just its own stiffness but nearly three times that when attached is of considerable benefit and saves vehicle weight and increases range.

It should be understood that identical element symbols used on multiple figures refer to the same component, or components of equal functionality. Additionally, the accompanying figures are only meant to illustrate, not limit, the scope of the invention and should not be considered to be to scale.

Systems and methods have been described in general terms as an aid to understanding details of the invention. In some instances, well-known structures, materials, and/or operations have not been specifically shown or described in detail to avoid obscuring aspects of the invention. In other instances, specific details have been given in order to provide a thorough understanding of the invention. One skilled in the relevant art will recognize that the invention may be embodied in other specific forms, for example to adapt to a particular system or apparatus or situation or material or component, without departing from the spirit or essential characteristics thereof. Therefore the disclosures and descriptions herein are intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims. 

What is claimed is:
 1. An energy absorbing and distributing side impact system for a vehicle, the system comprising: first and second side sills, each of the first and second sills comprising multiple longitudinal channels, at least an upper longitudinal channel positioned above a vehicle floor panel and at least a lower longitudinal channel positioned below the vehicle floor panel; a battery enclosure mounted between front and rear suspensions of the vehicle, the battery enclosure having a first side member attached to the first side sill, and a second side member attached to the second side sill; cross-members integrated into the battery enclosure; and one or more bolts each extending though a respective opening in one of the cross-members and extending to an opposite side of the vehicle floor panel from the cross-member.
 2. The energy absorbing and distributing side impact system of claim 1, wherein the battery enclosure is an aerodynamic device having a design that improves aerodynamic performance of the vehicle.
 3. The energy absorbing and distributing side impact system of claim 2, wherein a bottom of the battery enclosure is substantially flat.
 4. The energy absorbing and distributing side impact system of claim 2, wherein front wheel arch edges on the battery enclosure are radiused to allow air from a front wheel to transition to an underside of the vehicle.
 5. The energy absorbing and distributing side impact system of claim 1, further comprising a gasket material that covers a gap formed between a top of the battery enclosure and an underside of the vehicle floor panel.
 6. The energy absorbing and distributing side impact system of claim 1, further comprising a seat mounting structure on the opposite side of the vehicle floor panel from the cross-member, the seat mounting structure held by at least the one or more bolts.
 7. The energy absorbing and distributing side impact system of claim 6, wherein the seat mounting structure further comprises at least one threaded seat mount.
 8. The energy absorbing and distributing side impact system of claim 6, wherein the bolt is held by a nut on a same side of the vehicle floor panel as the seat mounting structure.
 9. The energy absorbing and distributing side impact system of claim 1, further comprising a sub-frame mount integrated into the battery enclosure.
 10. The energy absorbing and distributing side impact system of claim 9, further comprising a sub-frame bushing mounted in double shear with a structure on a bottom plate of the battery enclosure.
 11. The energy absorbing and distributing side impact system of claim 1, wherein the battery enclosure is an integral part of a load path for managing loads in frontal impact.
 12. The energy absorbing and distributing side impact system of claim 11, configured so that a majority of the loads are fed from rails at a front of the vehicle into a torque box.
 13. The energy absorbing and distributing side impact system of claim 12, further comprising a secondary load path that feeds loads from a lower portion of the vehicle along a sub-frame and into a rear mount of the sub-frame coupled to the battery enclosure and to the torque box.
 14. The energy absorbing and distributing side impact system of claim 12, wherein the battery enclosure is configured to feed the loads along its members to the first and second side sills.
 15. The energy absorbing and distributing side impact system of claim 1, wherein a bottom plate of the battery enclosure is configured to provide sheer stiffness to mounting locations of a steering rack.
 16. The energy absorbing and distributing side impact system of claim 1, wherein the first side member is attached to the lower longitudinal channel of the first side sill and the second side member is attached to the lower longitudinal channel of the second side sill.
 17. The energy absorbing and distributing side impact system of claim 1, wherein each of the cross-members comprises an upper portion and a lower portion, wherein a spacing between the upper and lower portions is configured to receive a mounting bracket for at least one battery module in the battery enclosure.
 18. The energy absorbing and distributing side impact system of claim 1, wherein each of the first and second side members comprises at least first through fourth lumens, wherein at least the first, second and third lumens are arranged in an essentially vertical configuration, and wherein at least the fourth lumen is arranged outward of the third lumen.
 19. The energy absorbing and distributing side impact system of claim 1, wherein the cross-members segregate the battery enclosure into full-width sections and at least one other section, each of the full-width sections fitting two battery modules side-by-side in a direction of travel, the other section fitting two stacked modules.
 20. An energy absorbing and distributing side impact system for a vehicle, the system comprising: first and second side sills, each of the first and second sills comprising multiple longitudinal channels, at least an upper longitudinal channel positioned above a vehicle floor panel and at least a lower longitudinal channel positioned below the vehicle floor panel; and means for improving aerodynamic performance of the vehicle, for providing noise and thermal insulation, for providing a mounting structure for a seat in the vehicle, for providing an attachment for a sub-frame, for providing a load path for loads in a frontal impact, for providing protection of an occupant in a side impact, and for providing stiffness to a mounting location of a steering rack. 